The present disclosure relates to a transmission device that changes a speed of power transmitted from a motor of a vehicle to an input shaft and transmits the resultant power to an output shaft.
Conventionally, a transmission device that includes two single-pinion type planetary gears, what is called a Simpson compound planetary gear mechanism, four clutches, and two brakes are known as a transmission device of such a type. (see U.S. Pat. No. 8,202,190, for example). The compound planetary gear mechanism included in such a transmission device includes an input element connected to an input shaft, a fixable element selectively non-rotatably held stationary by a brake, and first and second output elements. The first output element is selectively connected to another rotational element by a first clutch, and the second output element is selectively connected to yet another rotational element by a second clutch.